"""
From https://twitter.com/Al_Grigor/status/1357028887209902088
Most candidates cannot solve this interview problem:
* Input: "aaaabbbcca"
* Output: [("a", 4), ("b", 3), ("c", 2), ("a", 1)]
Write a function that converts the input to the output
I ask it in the screening interview and give it 25 minutes
How would you solve it?
"""

def rle(x):
    res = [[x[0],1]]
    for i in range(1,len(x)):
        if x[i] == x[i-1]:
            res[-1][1]+=1
        else:
            res.append([x[i],1])
    return [tuple(j) for j in res]


if __name__=="__main__":
    print(rle("aaaabbbcca"))